


Shifted Fun

by simplywrite



Category: The Avengers (Marvel) - All Media Types
Genre: Anal Fingering, Animalistic, Barebacking, Bestiality, Bottom Tony Stark, Established Relationship, Human Tony, Knotting, M/M, Other, Past Relationship(s), Rough Sex, Shameless Smut, Shifted Sex, Shifter Bucky Barnes, Shifter Verse, Shifter/Human, Size Difference, Size Kink, Smut, Top Bucky Barnes, Wolf Shifter Bucky Barnes, so i'm also going to tag this as, to be safe
Language: English
Status: Completed
Published: 2018-10-29
Updated: 2018-10-29
Packaged: 2019-08-09 15:57:19
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,764
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16452908
Author URL: https://archiveofourown.org/users/simplywrite/pseuds/simplywrite
Summary: Tony might be a human but he was fully aware that shifters had completely different needs. This was something Bucky needed and Tony was more than happy to provide it.





	Shifted Fun

**Author's Note:**

> This was written for a friend who really wanted full shifter WinterIron smut for her birthday.

Tony shuddered at the hungry, near feral look in his boyfriend’s eyes. He knew how much it meant to his shifter boyfriend, how important this was for shifters, when a mate, or potential mate in Tony’s case, completely accepted them. He was also aware of how important it was for a canine shifter to frequently indulge in claiming their partner in their shifted form.

It was something Bucky _needed_ and he’d finally gotten the courage to ask Tony despite the obvious trepidation Tony could practically read in Bucky’s eyes when he’d first asked.

Tony slicked his fingers with the special canine shifter lube his boyfriend had purchased while Bucky watched, his heart pounding in his chest in anticipation, before Tony shifted his body and reaching back to rub against his dry hole. The sensation had his breathing hitching and his body flushing in arousal.

It wasn’t the first time they had fucked but it was the very first time he was letting Bucky fuck him while his boyfriend was fully shifted.

Tony worked his finger inside, rubbing lube against his inner walls, as he set about loosening his hole for the truly monstrous dick he _knew_ was going to be fucking him in a matter of moments. One finger became two and two became three as Bucky watched, breathing rough, as Tony moaned and pushed back into his own fingers. He loved putting on a show for Bucky, whether it was fingers or toys, while his boyfriend waited to fuck him through the mattress or against the nearest surface.

His own dick hung hard and heavy between his legs, neglected and aching, as he added more and more lube to his ass.

“Make sure you’re nice and wet, doll.” Bucky’s voice was rough and dark sounding. A glance over revealed how worked up his boyfriend was watching him preparing himself. “It’ll make it easier and more enjoyable.”

He took Bucky’s word for it.

Tony looked over at the bottle, mentally shrugged, and picked it up. He pushed the end against his loosened hole and squirted the lube directly into his ass. The sensation had him jerking but he added more and more before discarding the lube bottle. It lazily tried leaking out of his ass but Tony pushed the lube back inside and groaned.

He felt wet, messy and loose—ready to be fucked by an unnaturally large wolf.

The bed dipped with Bucky’s weight as warm, strong hands started to shift him around. Bucky guided him so his face was pressed against their cool sheets and his knees were pressed to the mattress. A firm hand moved his legs apart, wider and wider, until there was a dull ache in his hips. Next Bucky pressed softly against his back until it was bowed, his ass raised high in offering where he was positioned in the center of the bed.

“That’s the position, doll.” Bucky’s voice had gone low with his arousal, “Whenever we fuck in my shifted form _this_ is the position you’ll need to maintain.”

Tony felt a warm hand pet his flank, moving idly, as warm breath brushed against his exposed hole. “Only this one?” he swallowed when his voice came out gravelly.

“Yes.” There was a brief pause as though Bucky was almost hesitant. “It’s the perfect position for mounting a—” really Bucky didn’t _need_ to explain _why_ he cut himself off. Tony was fully aware of what the one in _this_ position was typically called.

“For mounting a bitch.”

“…yes.”

There was something _wrong_ about that but even though Tony didn’t _understand_ the dynamics of a canine shifter, or any shifter because he was purely human, he was aware of them in the technical sense. He’d done some research the few times he’d been in a relationship with a shifter but this was his first canine shifter and Bucky had been rather hesitant to ask.

Tony had figured it out and when Bucky finally asked he had said _yes_. He loved Bucky and he would love all of Bucky. Besides it wasn’t his first shifted fuck but it was the first one with someone he actually _loved_.

“Ready?”

He was practically vibrating with anticipation. “Don’t I look ready?” he teased trying to lighten the intense look.

Behind him Bucky shifted and Tony felt fur brush against his naked body. A glance at Bucky revealed the massive, so very massive, black wolf occupying their huge bed. Tony’s fingers curled in the sheets as his heart pounded wildly in his chest and his muscles trembled.

Bucky’s wolf was gigantic but he was even more impressive because of the bastardized super soldier serum pumping through his veins. It’s why Tony anticipated that _this_ was going to be very different from an actual wolf _mating_ —which he’d Googled in curiosity after agreeing.

There was a low grumble that practically shook the bed as Wolf-Bucky shifted and more fur brushed against Tony. He bit his lip and made sure his position hadn’t changed as Wolf-Bucky moved to mount him.

A hot, thick and massive wolf dick brushed against him causing Tony to freeze. He could feel the way Wolf-Bucky’s front legs gripped his trembling body as the wolf shifted forward and started rutting up against his ass.

It brushed against his wet hole, missing it’s target, as Wolf-Bucky’s grip tightened and his thrusts became a bit more frantic until the tip of Wolf-Bucky’s dick managed to catch on Tony’s loosened hole. There was a second, one heart stopping second, before his shifted boyfriend _slammed_ balls deep into his ass with one hard, vicious snap of his furry hips.

Tony _howled_ at the sensation of suddenly being split wide open and stuffed full of the shifter’s dick.

He felt Wolf-Bucky still, body trembling, until Tony managed a wrecked _I’m fine_. That seemed to be all his boyfriend was waiting for. Immediately Wolf-Bucky started fucking him—it was hard, fast, rough and mindlessly greedy in the way only an _animal_ could manage. Tony flushed when he realized he could _hear_ the way the shifter’s dick plowed through the liberal amount of lube coating the inside of his ass.

It was a wet, filthy kind of sound that made the fact that Tony was, essentially, being fucked by a giant _wolf_ even more dirty-bad-wrong.

There was nothing Tony could really do in this position, in the bitch position. Wolf-Bucky was ramming into him, the force causing his body to shift, to the point that Tony could hear the headboard knocking against the wall. Tony had _never_ been fucked like this before in his entire life and he’d been in the middle of a very messy gangbang that had lasted for hours and hours.

Hot, wet breath brushed against the back of his neck as Wolf-Bucky kept fucking into him. It was clear, by this point, that Bucky’s wolf form had gained the added benefit of the super soldier serum because a normal wolf would have been done by now.

Tony shifted on his knees and jerked when Wolf-Bucky started _nailing_ his prostate with each hard, greedy thrust.

He hardly recognized his own voice when loud, broken keening moans started spilling from his parted lips. Tony could feel his orgasm building where it was twisting in his gut, tightening at the base of his spine, as Wolf-Bucky kept fucking in and out of him at an increasing pace Tony could have never met.

It took everything in him to maintain his position for Wolf-Bucky to mount, fuck and _knot_.

Tony was panting, whining, trembling and shuddering as his own pleasure burned through him with each hit to his prostate. His ass was clenching down on Wolf-Bucky’s dick and earning low, rumbling growls from his boyfriend and spurring Wolf-Bucky on so he fucked into Tony even harder.

There were probably going to be bruises where Wolf-Bucky was gripping him and his ass was going to ache for days but it felt surprisingly good. It was nothing on the few shifters Tony had been with in the past who had decided to fuck Tony in their shifted forms.

This was something else.

It was easy to lose track of time as Wolf-Bucky greedily fucked him. The feeling of something bigger, something _round_ , bumping against his hole had Tony snapping back from the haze of pleasure to focus on everything—from the sounds of filthy sex, to the burn of his muscles, the way his legs were trembling and his body was swaying with the force behind Wolf-Bucky’s thrusts.

Wolf-Bucky growled lowly and started viciously rutting against Tony’s ass, grinding against Tony’s stuffed hole, until his _knot_ started to push past the resistance of Tony’s rim. It _burned_ and Tony’s mouth fell open on a silent wail at the sensation of Wolf-Bucky’s knot forcing its way inside, swelling and splitting his ass wide open.

Tony jerked at the sensation and startled when he realized he could _feel_ Wolf-Bucky’s release _pouring_ into his aching ass. The feeling had him shuddering and groaning lowly.

“Fuck, Winter Wolf, _fuck_.”

He could feel his arousal fading and didn’t hesitate to reach under himself, grip his neglected dick and start jerking himself off. His eyes fluttered closed as he dragged himself towards his own orgasm. It didn’t take much, he was already on the edge from repeated hits to his prostate, to send himself spiraling into pleasure.

Tony panted against the sheets, shuddering and jerking, as his orgasm rushed through him and his ass clenched down on Wolf-Bucky’s enormous knot. Behind him Wolf-Bucky grumbled.

“Don’t think I can keep this up.” He slurred, “Lay down?”

Fortunately Wolf-Bucky seemed to understand and, after a few painful moments of having that knot tugging on his stretched rim, Tony was sprawled out on his belly with Wolf-Bucky settled over him with his knot firmly locked in Tony’s poor aching ass.

“How long does it last? Ten? Twenty minutes?”

He looked back at Bucky and could tell by the expression on the wolf’s face that it was longer. Probably so much longer.

“Good thing I didn’t have plans.”

In response Wolf-Bucky’s furry hips jerked forward and Tony felt another _flood_ of come empty into him. He wasn’t sure he was ever going to get used to _that_ feeling.

“We’re going to be making some canine shifter friendly purchases, Winter Wolf. I think one of those padded stands is going to be necessary in the future.” It would certainly make maintaining his position for that long far easier and enjoyable whenever Bucky needed to let the wolf out in the bedroom.

**Author's Note:**

> It's been awhile since I've posted anything on this site but I wanted a fresh start and opened this account. I hope you all enjoyed my fic as much as my friend did. I know this isn't something typically found in the Marvel Fandom but if it's well received I could see about posting more like this :) 
> 
>  
> 
> If you enjoyed my fic please leave a comment! It only takes a few moments and it would mean a lot to hear what you thought of my writing. If you happen to have a suggestion for another uncommon kink featuring Tony I would love to hear it!


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